Strained channel regions have been used to increase carrier mobility because strained channel regions lower the energy of conduction states therein. Lowering surface roughness scattering has been studied to further increase carrier mobility. Reduced surface roughness scattering in strained silicon inversion layers is investigated and disclosed, for example, in a paper by Chris Bowen and Ryan Hatcher entitled “Physical insight into reduced surface roughness scattering in strained silicon inversion layers”, Applied Physics Letters 101, 073504 (2012), the disclosure of which is incorporated herein by reference in its entirety. Further, electronic properties of strained-layer superlattices are studied and disclosed, for example, in a paper by S. Satpathy et al. entitled “Electronic properties of the (100) (Si)/(Ge) strained-layer superlattices”, Physical Review B, Volume 38, Number 18, pages 13237-13245, 15 Dec. 1988.